﻿ Soil support angle functions [SUPANG]

# Soil support angle functions [SUPANG]

Specification of soil support angle function at bottom of cross-section, specified along pipeline axis (Input Table)

Table description:

Through the input data table SUPANG the support angle of the soil underneath the pipeline is specified.

As the soil support angle may vary with the magnitude of the vertical soil reaction underneath the pipeline relative to the bearing capacity of the soil, the possibility is provided to define a variable soil supporting angle depending on the ratio of the calculated soil reaction and the bearing capacity of the soil.

The calculation of the vertical soil reaction underneath the pipeline takes into account the vertical component of the lateral soil reaction as a result of the overall behaviour of the pipeline together with the specified soil loads (SOILNB (+TOPLOAD)). The resulting soil reaction is used to calculate the ratio value RVS().

The supporting angle ANG() depends on the ratio : RVS()= vertical soil reaction underneath pipeline at a cross section/ bearing capacity of the soil * 100 (in percent). For values of RVS() less or equal RVSL ANG() is a constant equal to ANGMIN, for RVS() greater or equal to RVSH ANG() is a constant equal to ANGMAX.

Between RVSL and RVSH ANG() varies between ANGMIN and ANGMAX as a specified function of RVS().

One out of three curves must be specified to describe the relation of ANG() to RVS() between RVSL and RVSH.

 LIN: a linear relationship between (ANGMIN,RVSL) and (ANGMAX,RVSH) SIN: a sinusoidal relationship, where a sine curve is placed between the points (ANGMIN,RVSL) and (ANGMAX,RVSH) with a vertical derivative with respect to ANG() at (ANGMAX,RVSH). RVSH is the amplitude of the sine and the node is situated on the ANG() axis. For the default case the node of the sine coincides with the origin of the ANG()-RVS() graph. PAR: a parabolic relationship, where a parabolic curve is placed between the points (ANGMIN,RVSL) and (ANGMAX,RVSH) with a horizontal derivative with respect to RVS() at (ANGMAX,RVSH).

If ANG() must be a constant for all values of RVS(), make ANGMIN=ANGMAX=required value, RVSL, RVSH and CURVE = default.

H610142, last changed: 2009-07-16